Poa lettermanii |
Poa ×nematophylla |
|
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Letterman bluegrass, Letterman's blue grass |
bluegrass |
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Habit | Plants perennial; not glaucous; densely tufted, not stoloniferous, not rhizomatous. | Plants perennial; densely tufted, not stoloniferous, not rhizomatous. |
Culms | 1-12 cm, slender. |
10-35 cm, erect or the bases decumbent; nodes terete, 0-1 exserted. |
Sheaths | closed for 1/6 – 1/4 their length, terete; ligules 1-3 mm, milky white to hyaline, smooth; blades 0.5-2 mm wide, flat or folded, or slightly inrolled, thin, without papillae (at 100x), apices narrowly prow-shaped. |
closed for 1/4-3/4 their length, terete, apices acuminate; innovation blades 0.5-1(2) mm wide, involute, moderately thick, moderately firm, abaxial surfaces smooth or scabrous, adaxial surfaces usually densely scabrous or hispidulous; cauline blades usually gradually reduced distally, 0.5-1(2) mm wide, flat, folded, or involute, thin, sometimes withering, abaxial surfaces smooth or scabrous, apices narrowly prow-shaped, sometimes the flag leaf blades vestigial. |
Basal branching | all or mainly intra-vaginal. |
intra-vaginal. |
Panicles | 1-3 cm, erect, contracted, usually exserted from the sheaths; branches to 1.5 cm, erect to steeply ascending, slender, sulcate or angled, smooth or the angles sparsely scabrous; pedicels shorter than the spikelets. |
2-8 cm, erect, narrowly lanceoloid to ovoid, contracted, congested; nodes with 1-2 branches; branches 0.5-3 cm, erect, terete to angled, scabrous. |
Spikelets | 3-4 mm, laterally compressed, green or anthocyanic; florets 2-3; rachilla internodes shorter than 1 mm, smooth. |
4-8 mm, lengths to 3 times widths, broadly lanceolate to narrowly ovate, laterally compressed, not sexually dimorphic; florets 2-5; rachilla internodes 0.5-1.2 mm, smooth or scabrous. |
Glumes | usually equaling or exceeding the lowest lemmas, sometimes also equaling or exceeding the upper florets, lanceolate to broadly lanceolate, distinctly keeled, keels smooth; lower glumes 3-veined; calluses glabrous; lemmas 2.5-3 mm, lanceolate, distinctly keeled, thin, usually glabrous, keels and marginal veins rarely sparsely puberulent proximally, apices acute; palea keels scabrous; anthers 0.2-0.8 mm. |
lanceolate, distinctly keeled; lower glumes 3-veined, distinctly shorter than the lowest lemmas; calluses glabrous; lemmas 4-7 mm, lanceolate, distinctly keeled, membranous, keels and marginal veins usually softly puberulent, sometimes short-villous, intercostal regions usually glabrous, infrequently softly puberulent proximally, lateral veins moderately prominent, margins glabrous, apices acute; palea keels scabrous; anthers mostly vestigial (0.1-0.2 mm), rarely 2-3 mm. |
2n | = 14. |
= unknown. |
Poa lettermanii |
Poa ×nematophylla |
|
Distribution |
CA; CO; ID; MT; NV; OR; UT; WA; WY; AB; BC
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CO; ID; MT; ND; UT; WY; AB; BC; MB; SK |
Discussion | Poa lettermanii grows on rocky slopes of the highest peaks and ridges in the alpine zone, from northern British Columbia to western Alberta and south to California and Colorado, usually in the shelter of rocks or on mesic to wet, frost-scarred slopes. It is one of only three known diploid Poa species native to the Western Hemisphere. Its glabrous calluses and lemmas usually distinguish it from P. abbreviata (p. 582); it also differs in having flat or folded leaf blades, and shorter spikelets with glumes that are longer than the adjacent florets. Poa montevansii E.H. Kelso is tentatively included here, although its slightly longer lemmas that slightly exceed the glumes suggest that it may represent rare, glabrous forms of P. abbreviata. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Poa ×nematophylla is believed to consists of hybrids between P. cusickii subsp. pallida (see previous) and P. fendleriana (p. 556). It is mostly pistillate and apomictic; few staminate plants have been found. It usually resembles P. cusickii most, but grades towards P. fendleriana. It tends to grow on drier slopes than either parent, mainly in and around sagebrush desert/forest interfaces. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 24, p. 580. | FNA vol. 24, p. 562. |
Parent taxa | Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Abbreviatae | Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Madropoa > subsect. Epiles |
Sibling taxa | ||
Synonyms | P. mor.tevansi | P. cusickii subsp. pubens |
Name authority | Vasey | Rydb. |
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